@snowyang26 his "wife" doesn't actually want him, said she'd never love him, didn't allow him TO kiss her JUST ONCE ON THEIR WEDDING Ceremony or even have a fking honeymoon. Of course he wouldn't invite anyone to their wedding when it's a sham. Why this guy didn't just go around her and marry her sister anyways is an exercise in forced writing. Why this guy continues to put up with such a woman is also an exercise in forced WRITING and fans needing him to stick around for their self insert FMC. Besides everything has been to what she wants in the first place, otherwise he would've married the sister.
His friend goes on about how his wife is suffering but she's probably loving being alone from him. If this wasn't a shojo wouldn't be surprised if she cheated on him and expected him to put up with it too.